package cn.edu.scau.cmi.shishuai.exercise9;

public class EncryptAndDecrypt {
	String encrypt(String sourceString, String password) {
		char [] p = password.toCharArray();
		int n = p.length;
		char [] c = sourceString.toCharArray();
		int m = c.length;
		for(int k = 0; k < m; k++) {
			int mima = c[k] + p[k%n];
			c[k] = (char)mima;
		}
		return new String(c);
	}
	
	String decrypt(String sourceString, String password) {
		char [] p = password.toCharArray();
		int n = p.length;
		char [] c = sourceString.toCharArray();
		int m = c.length;
		for(int k = 0; k < m; k++) {
			int mima = c[k] - p[k%n];
			c[k] = (char)mima;
		}
		return new String(c);
	}
}
